The four initial floors of the fourteen-storey Reliance Building, designed by Charles B. Atwood of Daniel Burnham's office and the structural engineer E.C. Shankland, were erected in 1890. This being the first comprehensive achievement of the system now known as Chicago construction, was repeated innumerable times in Chicago in the building boom that lasted from 1890 to 1893. It consisted of a riveted steel-frame superstructure, hollow-tile flooring on steel joists, plaster fire-proofing, perimeter bay windows filled with plate glass, steel-trussed wind bracing and bedrock concrete caissons sometimes extending for as much as 125 feet beneath the footing... Source, Kenneth Frampton and Yukio Futagawa, Modern Architecture 1851-1945, p 63. / 'The Reliance Building is one of the greatest icons of American architecture. It is proof that the early skyscraper style, known as the Chicago School, was not just a precursor of modern architecture. This building is one of the finest high-rise buildings of any time. This sixteen-story building is one of the first glass tower skyscrapers. The framing for the top ten floors was done in fifteen days. Designer Charles Atwood used glass at every opportunity. He folded the bay windows out from the frame to completely hide the columns and balanced huge picture windows with narrow ones of double-hung sashes. It was originally designed in 1890 by John W. Root. The pre-existing building on the site was temporarily supported while foundations and some structure on the ground level floor were constructed. This portion of the building designed by Root is distinguished by its granite cladding. After Root's death, Charles B. Atwood redesigned the building, altering the building's aesthetics. Instead of the heavy masonry articulation designed by Root, Atwood used glazed terra-cotta which appears to be wrapped around the structural frame and projecting window bays.' Source: http://members.aol.com/dahlia773/reliance.htm